The subject matter disclosed herein relates generally to industrial controllers, and more specifically, to industrial controllers using integrated circuit elements with watchdog timing circuits.
Industrial controllers are specialized computer systems used for the control of industrial processes or machinery, for example, in a factory environment. Generally, an industrial controller executes a stored control program that reads inputs from a variety of sensors associated with the controlled process and machine and, sensing the conditions of the process or machine and based on those inputs and a stored control program, calculates a set of outputs used to control actuators controlling the process or machine.
Industrial controllers differ from conventional computers in a number of ways. Physically, they are constructed to be substantially more robust against shock and damage and to better resist external contaminants and extreme environmental conditions than conventional computers. The processors and operating systems are optimized for real-time control and are programmed with languages designed to permit rapid development of control programs tailored to a constantly varying set of machine control or process control applications.
Generally, the controllers have a highly modular architecture, for example, that allows different numbers and types of input and output modules to be used to connect the controller to the process or machinery to be controlled. This modularity is facilitated through the use of special “control networks” suitable for highly reliable and available real-time communication. Such control networks (for example, ControlNet or EtherNet/IP) differ from standard communication networks (such as Ethernet) by guaranteeing maximum communication delays by pre-scheduling the communication capacity of the network, and/or providing redundant communication capabilities for high-availability.
As industrial controllers are typically used to control industrial processes and machinery, industrial controllers typically require greater safety and reliability than conventional computers. For example, unlike conventional computers, a failure for an industrial controller in a manufacturing environment could potentially result in costly manufacturing downtime, injury, and the like. Moreover, increasing complexity of industrial control systems typically results in increasing numbers of parts with each susceptible to some amount of failure. Consequently, it is desirable to provide an efficient and cost effective way to increase the safety and/or reliability of industrial controllers and industrial control systems.